The present invention relates generally to keyboard musical instruments, such as pianos, and more particularly to a technique for sensing given performance-related movement and determining a time point of string-striking operation on the basis of the sensed results.
The present invention also relates to a technique which is suitable applicable to musical instruments, such as pianos, arranged to generate tones on the basis of operation of displacement members that reciprocatively move in response to movement of performance operators, and which, in such musical instruments, determines time points string-striking movement or operation on the basis of the operation of the displacement members.
In the field of keyboard musical instruments, such as automatic player pianos, it has been a common practice to detect movement of keys, hammers, etc. via sensors so as to record detected results as performance data or supply the detected results to an electronic tone generator for electronic generation of tones. In creating performance data etc. in such automatic player pianos by use of detected time points and velocities of string-striking operation, there is a need to acquire string-striking time points and velocities with an enhanced accuracy; therefore, automatic player pianos have been known which are provided with hammer sensors for detecting operation or movement of hammers. Japanese Patent Application Laid-open Publication No. 2001-175262 discloses an example of a keyboard musical instrument provided with hammer sensors. The disclosed keyboard musical instrument includes hammer sensors (or successive physical amount sensors) for successively detecting displacement of corresponding hammer shanks. As one of the keys is operated in the disclosed keyboard musical instrument, the hammer sensor (successive physical amount sensor) successively detects physical amounts (e.g., position, velocity or acceleration) of movement or displacement of the corresponding hammer. Using such detection results, the keyboard musical instrument acquires various performance-related information, such as (1) a time point at which the hammer has started moving (i.e., hammer-movement start time point), (2) a time point at which the corresponding string has been struck (i.e., string-striking time point), (3) a moving velocity of the hammer (i.e., hammer velocity) immediately before the string striking, (4) a time point at which the key has been depressed (i.e., key-depression time point), (5) a back check time point, (6) a time point at which the back check has disengaged, (7) a hammer velocity after the back check has disengaged, (8) a time point at which the damper has started returning to its home or rest position (i.e., damper-return start time point), (9) a time point at which the hammer has stopped moving (i.e., hammer-movement end time point), and (10) a time point at which the key has been released (i.e., key-release time point). Namely, the disclosed keyboard musical instrument is arranged to successively detect various physical amounts related to the movement of the hammer, perform arithmetic operations on the sensor outputs as appropriate to acquire various information as enumerated above and then create performance data based on the acquired various information. In this way, the disclosed keyboard musical instrument permits creation of performance data capable of reproducing a performance with an increased accuracy and precision.
For example, in order to generate the information of the string-striking time point and hammer velocity immediately before string striking, the conventional apparatus, represented by the disclosed instrument of the No. 2001-175262 publication, determine whether or not any one of the strings has been struck, on the basis of a comparison between the outputs from the successive physical amount sensor and a predetermined reference value, and use the determination result to generate the required information. Because, the above-mentioned various information is generated on the basis of the outputs from the successive physical amount sensor and predetermined reference value, the conventional apparatus would present the inconvenience that the various information tends to fail to accurately correspond to actual performance states (operating states of the hammer) if input/output characteristics of the sensor vary due to variation in temperature, deterioration over time (i.e., aged deterioration or aging), etc., as a result of which the output information would undesirably become inaccurate.
Further, according to the conventional apparatus arrangements, represented by those of the disclosed keyboard musical instrument in the laid-open publication, in order to generate various information related to a piano performance, a control system of the apparatus is arranged to judges operating states of the hammer through hammer-operation determination processes, such as a determination of a start of the hammer movement and a determination as to whether the hammer in question has struck the string (i.e., string-striking determination). Specifically, it has been conventional to determine the operating states of the hammer by comparing the outputs of the hammer sensor and predetermined threshold values, to thereby associate the sensor outputs with operating positions of the hammer and then judge the operating states of the hammer on the basis of the operating positions of the hammer. However, with the conventional technique, the string-striking determination, intended to acquire the string-striking time point etc., is made solely on the basis of only movement of the hammer when approaching the string (i.e. only movement of the hammer before striking the string, so that the determination as to whether or not the hammer has struck the string (i.e., string-striking determination) tends to be unreliable. Furthermore, input/output characteristics of an optical sensor, used as the successive physical amount sensor, may present unwanted variation over time (i.e., aging), such as a light amount decrease during use of the sensor. However, the conventional apparatus can not appropriately deal with such undesired variation over time in the input/output characteristics of the optical sensor (e.g., light amount decrease).